Riser block



FIG. 1 is a left side perspective view of a riser block;

FIG. 2 is a front elevational view of FIG. 1;

FIG. 3 is a rear elevational view of FIG. 1;

FIG. 4 is a right side elevational view of FIG. 1;

FIG. 5 is a left side elevational view of FIG. 1;

FIG. 6 is a top plan view of FIG. 1; and,

FIG. 7 is a bottom plan view of FIG. 1. 

I claim the ornamental design for a riser block, as shown and described. 